This invention relates to a fluid for electrical discharge machining. In order to improve electrical discharge machining performance, there has conventionally been used electrical discharge machining fluid consisting of an emulsion of water mixed with electrical discharge machining oil in the presence of a surfactant. With such an electrical discharge machine fluid, water in the form of globules distributed in the electrical discharge machining oil, in the space between the workpiece and electrode was condensed explosively by the discharge, producing energy that was utilized to improve the electrical discharge machining performance.
However, with such electrical discharge machining fluids in which a surfactant is mixed in to emulsify the water, a drawback with this method is that tar adhering around the machined portion separates from said machined portion and becomes distributed in the machining fluid as globules 0.5-1.0.mu. in diameter, so the fluid darkens with the progress of the machining process, so that it becomes difficult to observe the portion being machined, and working efficiency thereby is decreased. It is extremely difficult to remove this tar from the fluid by filtering or the like, and consequently a solution to this problem has been sought.